SX-850 AWR-101 Resistor question

Those are entirely correct readings.

Just as I suspected, so
Replace R20 with a new resistor.

Leave the short in place for now, you can try lighting up the lamps to double check - the ONLY consequence is that R20 was supposed to dissipate some of the heat involved in throttling down 25v to 5.4 volts.

Each lamp (50mA = I = 0.05 amp) needs a watt of dissipation (V*I) (( 25 - 5 ) * .05), So one function lamp and no speaker lamps for now just to test. Then leave the wires disconnected until a resistor is procured.
 
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I will have to order one from Mouser. I love where I live, but electronic parts can be a wee bit scarce.

I assume this 100 ohm 3w metal oxide resistor is OK? Panasonic ERG-3SJ101A resistor

At the same time, I will place the order for the Power Amp board (AWH-059) that is listed in Post #44 of this thread. I believe some diodes were mentioned previously in this thread, I'll look into ordering those as well.

Leave the short in place for now, you can try lighting up the lamps to double check - the ONLY consequence is that R20 was supposed to dissipate some of the heat involved in throttling down 25v to 5.4 volts.

Each lamp (50mA = I = 0.05 amp) needs a watt of dissipation (V*I) (( 25 - 5 ) * .05), So one function lamp and no speaker lamps for now just to test.

With the wires on pins 2 and 3 still disconnected, I gave that a try. Speaker buttons off, I went through each function button, but nothing lit up. i jiggled the buttons back to "no function" mode.

I reconnected those two wires, and powered up the receiver again. Speaker buttons still off, I then tapped through each of the function buttons. Each one lit up beautifully.

I shut it all down and re-disconnected the wires; I will place my Mouser order tomorrow. If you feel there ought to be any other components added (perhaps as "just in case") please let me know.

To refresh one's memory, I have already rebuilt the Power Supply board and the Protection Circuit board, and have replaced the following transistors:
EQ Amp board (AWF-011)

Q1: 2SA725: 512-KSA992FBU
Q2: 2SA725: 512-KSA992FBU
Q3: 2SC1313: 512-KSC1845FTA
Q4: 2SC1313: 512-KSC1845FTA
Q5: 2SC1313: 512-KSC1845FTA
Q6: 2SC1313: 512-KSC1845FTA

Flat Amp board (AWG-038)

Q5: 2SA725: 512-KSA992FBU
Q6: 2SA725: 512-KSA992FBU

Tone Amp board (AWG-039)

Q1: 2SC1312: 512-KSC1845FTA
Q2: 2SC1312: 512-KSC1845FTA

Power Amp board (AWH-059)

Q1: 2SA726: 512-KSA992FBU
Q2: 2SA726: 512-KSA992FBU
Q3: 2SA726: 512-KSA992FBU
Q4: 2SA726: 512-KSA992FBU
 
I love this Thread!
Hey what camera are you using for all these Gallery shots?
 
I will have to order one from Mouser. I love where I live, but electronic parts can be a wee bit scarce.

I assume this 100 ohm 3w metal oxide resistor is OK? Panasonic ERG-3SJ101A resistor

I don't see why not, as it is the one I specified a while back:

Check R20, 100 ohms 3 watts, metal oxide. mouser.com 667-ERG-3SJ101A 100 ohms 3 watts
I suspect it's badly damaged.

Don't order parts yet until we nail down the rest of the faults.
but no nailing down tonight.

Let's see the list before ordering too.
 
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I love this Thread!

Me too, can't wait to see how it turns out! ;)

Hey what camera are you using for all these Gallery shots?

It's a Nikon D3x with a 60mm Micro Nikkor for macro shots. It's my work camera, and it's been used for a lot of the images I've taken for our site (which is also something I built and maintain)(I wear a few different hats as Creative Director)

If you'd like, you can see it here: Crown Point Cabinetry website
 
I don't see why not, as it is the one I specified a while back:
Check R20, 100 ohms 3 watts, metal oxide. mouser.com 667-ERG-3SJ101A 100 ohms 3 watts
I suspect it's badly damaged.

Ooh, bazinga. So you did. Probably was tucked away in my subconscious because of that. :D

Don't order parts yet until we nail down the rest of the faults.
but no nailing down tonight.

Let's see the list before ordering too.

Okey-doke. I will compile it all and post it once it reaches that point of "OK, now it's time to order parts".
 
yes, I have to SEE the list you want to use, to be able say there's no problems (obsolete components, lower voltages, undersized transistors etc) with it.
 
Ok, here goes...

First, what I didn't put on the order:

TESTED OK
All diodes
Test results:
(1s2473) mouser 1n4148
D1: .714
D2: .720
D3: .721
D4: .705

(1s1885) mouser (n14004? or 625-SRP300G-E3?)
D7: .629
D8: .654
D9: .639
D10: .634


(Regarding the list below: I’ve already replaced Q1, Q2, Q3, and Q4 on the board, but left them on the list. Extras never hurt)
...........................................................................................
TO ORDER:
Power Amp Board (AWH-059)

C1: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
C2: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
C3: 1uF 25v CSSA: 647-UKL1H010KDDANA 1uF 50v
C4: 1uF 25v CSSA: 647-UKL1H010KDDANA 1uF 50v
C5: 33uF 16v CEA: 647-UPW1C330MDD 33uF 16v
C6: 33uF 16v CEA: 647-UPW1C330MDD 33uF 16v
C11: 330uF 10v CEA: 647-UPW1A331MPD 330uF 10v
C12: 330uF 10v CEA: 647-UPW1A331MPD 330uF 10v

Q1: 2SA726: 512-KSA992FBU
Q2: 2SA726: 512-KSA992FBU
Q3: 2SA726: 512-KSA992FBU
Q4: 2SA726: 512-KSA992FBU
Q5: 2SA818: 512-KSA1381ESTU
Q6: 2SA818: 512-KSA1381ESTU
Q7: 2SC1628: 512-KSC3503DSTU
Q8: 2SC1628: 512-KSC3503DSTU
Q9: 2SD381: 512-KSC2073TU
Q10: 2SD381: 512-KSC2073TU
Q11: 2SB536: 512-KSA940TU
Q12: 2SB536: 512-KSA940TU

512-KSA940TU pnp to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.62
512-KSC2073TU npn to-220 bce 150v 1.5a 25w 4mhz 40-140hfe $0.66

VR1: 10K ohm - 652-3266P-103LF-ND
VR2: 10K ohm - 652-3266P-103LF-ND
VR3: 100 ohm - 652-3386H-101LF-ND
VR4: 100 ohm - 652-3386H-101LF-ND

652-3386H-1-101LF VR3 bias 100 ohm 1 turn
652-3266P-1-103LF VR1 offset 10k 12 turn

R20 100 ohms, 3 watt 667-ERG-3SJ101A 100 ohms 3 watts

512-1n4004 added. pins 9, 10(cathode, the banded end)
................................................................................................
 
Latest update:

I ordered the parts for AWH-059, including the diodes I originally wasn't going to order. (side note: I actually ordered both types; 1n4004 and 625-srp300g-e3)

Removed and replaced:
C1, C2, C3, C4, C5, C6, C11, C12.
Q1, Q2, Q3, Q4,<--those were done previously Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12
R20
VR1, VR2, VR3, VR4

With everything replaced, I made an executive decision to put it all back together. First, I reconnected the cut wires 2 and 3 on the power supply board. Then I went back to AWH-059 and replaced D8 and D10 with the srp300g-e3's, then cleaned the old thermal paste from the output transistors and mica shields, applied new paste (non-conductive Ceramique 2) and reinstalled those. Lastly I resoldered the leads to STV-4h diode.

I placed the large heatsink back into position, and made sure the board was set so that no metal was being contacted. (I chose to leave the full metal shield that goes behind the board off in case further work was needed)

Then I built a DBT, plugged it into the wall, and plugged the 850 into the DBT.

I gave the board one more visual once-over, took a deep breath...and flicked the switch on the DBT.

The bulb glowed brightly, then dimmed. Nice! The relay didn't click, but to tell the truth, I don't know if it's supposed to with the DBT or not. The fact that it glowed brightly, then dimmed, was enough of a success for me.

I knew I wasn't out of the woods yet. I still had to adjust VR1, 2, 3, 4. Having never done the procedure, I was fairly certain they could not be properly adjusted while still plugged into the DBT. (post note: my previous searches for tickling the dragon turned up only the DBT and running the unit on low power for a while. I now discovered the trim pots can be adjusted while using the DBT to determine if the unit will power up safely)

I unplugged my 850 from the DBT, and plugged it into house current.

Making sure the volume was down and no speaker buttons depressed, I took a bigger breath, and flicked the power switch...

After a couple of seconds, the metallic click of the relay instantly became the sweetest sound in the world. I rested my head against the faceplate, just so thankful.

However, would the trim posts adjust to spec? The answer was yes. I was able to get VR1 and VR2 to near perfect (0.000 to 0.001) and VR3 and VR4 to 20mv.

I let the unit warm up for 10-15 minutes, and rechecked the trim pots. Just a tiny tweak was all that was required for VR1, VR2 and VR3, and VR4 was still spot on.

I then connected speakers, dialed in an FM station, and gave a little volume. Music flowed out of my JBL L-50's. I was grinning like a little kid.

I then shut it all down, and put everything back together. I hooked my receiver back into the lineup (an RG-2, SG-9500 equalizer, and RT-707 r-t-r) loaded up a tape, and hit play.

Yeah, big ol' kid grin. Again. :D

It's been a long couple of months, and I want to thank all that offered help, insight and thoughts. And a special thanks to Mark for his willingness to help track down what was going on. (I think, despite a good ohm reading, that R20 was the culprit?)

I ran the tape for a couple of hours last night on low volume, and am playing the other side as I type this. I haven't yet tried any significant volume.

I do have one question: I can't remember if it's normal for the function lamp to go brighter when turning OFF the speaker button? It doesn't matter which function button is depressed, each one gets brighter when the speaker button goes off. The only one unaffected is the Stereo lamp for FM. Its illumination stays constant. Oh, switching speaker inputs yields the same results, so plugging into Speaker B doesn't change the symptom (if it is one!)

If someone thinks there is a problem, I will start a new thread.
 
RE; Lamps, The speaker lamps and the function lamps are on the same supply and wired in parallel. When you turn off the speaker, you disconnect the lamp for that speaker and the rest of the lamps will get slightly brighter as the load on the supply decreases.

The stereo light isn't affected as it's only partially (one side) on that particular circuit. The other side is a variable voltage that balances the 1st side when the lamp is off and drops or grounds to turn on the lamp.

You can check the fuse for that circuit to see if it's the right size.
 
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